An error occurred while attaching module (Dynamicweb.Frontend.Content)

System.ArgumentException: An item with the same key has already been added. Key: GROUP58
   at System.Collections.Generic.Dictionary`2.TryInsert(TKey key, TValue value, InsertionBehavior behavior)
   at Dynamicweb.Ecommerce.Products.GroupService.GetSubgroups(Group group, Boolean showUnTranslated)
   at Dynamicweb.Ecommerce.ProductCatalog.ViewEngine.<>c__DisplayClass32_0.b__1()
   at Dynamicweb.Ecommerce.ProductCatalog.ViewEngine.FillGroup(ProductListViewModelSettings settings, Group group, ProductListViewModel model, ViewModelPropertyFiller`1 filler)
   at Dynamicweb.Ecommerce.ProductCatalog.ViewEngine.CreateView(ProductListViewModelSettings settings, Group group, IList`1 products)
   at Dynamicweb.Ecommerce.ProductCatalog.ViewModelFactory.CreateView(ProductListViewModelSettings settings, String groupId, IEnumerable`1 productAutoIds)
   at Dynamicweb.Ecommerce.ProductCatalog.ProductCatalogFrontend.RenderProductList(ProductCatalogSettings settings, QuerySettings querySettings, IQuery query, String groupId, Boolean feed, Boolean compare)
   at Dynamicweb.Ecommerce.ProductCatalog.ProductCatalogFrontend.GetModuleContent()
   at Dynamicweb.Frontend.Content.GetModuleOutput(Paragraph paragraph, PageView pageview)